Drilling fluids and methods of using same



Patented Jan. 20, 1953 LUNITED JESTATES PATENT OFFICE 3 DRILLING FLUIDS ZND METHODS OF USING AME "No Drawing. Application July 28, 1949, Serial No. 107,394

i 1210mm. 1

This invention relatestodrillingfiuids. In one of-its more specific'aspects, it'relatesto a drilling *fiuid comprising solutions (andby solutions *we mean to include" dispersions and suspensions) of "cellulose which are not precipitated nor regenera-ted in any's'ubstantialdegree bydilution with waterpr the 'usual'dilute salts contained in the "conn'ate water'of anoil welll formation or by the heat or cold generally obtainable in a well. In "another sp'ecific'aspect, it relates to a'dr'illing'fluid comprising sulfonated' cellulose derivative. In still another specific aspect; it relates to the meth- -'ods o'fusing'such'celluloses for controlling viscosity, gel strength, Water loss and filter cake thickness of oil welldrillingfiuids.

This application is a continuation-in-part of our copending application, Serial No. 626,895, filed November 5, 1945, now abandoned.

Inthe art of drilling Wells, especially drilling wellsby the rotary method, it is necessary to use a drilling. mud or drilling fluid, as is well understood .inthe art. The drilling mudlubricates the drill stem, carries the cuttings to the surface of the well,.cools the drill bit and forms a filtercake on the Walls of the well to prevent the loss of at least any substantial amount of water from the drilling mudto the natural formationsv of the well. In order to. perform. these important functions properly, .the drilling-mudmusthave suitable viscosity and other-lthixatropicv properties at all times.

The. principal 'object of our: invention is to produce a drillinggnud whichcan be..used in sub- .stantiallyall formations with reduced water, loss,

.anm' filtergacaiiey and .proper viscosity .and...gel

strength,

Another object of our invention is to provide an improved drilling fluid.

Still another object of our invention is to providear'i improved method'iof drilling.

Anotherobject is to provide a "drilling mud additive 'suitable'ior imparting proper viscosity, I: "gel strength, water-lossy-andfilter cake thickness to well. drilling fluids.

2 Anotherobjectof' our invention is to provide .-.a::drilling @mud-containinga a-soluble (which inticludeseidispersible';Land suspendable) sulfonated "cellulose derivative which is not precipitated .or wregeneratedzin any substantial degree by dilution with. water or by' contact" with electrolytes norsmally encountered in drilling.

Num'erous :other objects I and advantages of this invention will be apparent to those skilled in the art uponreadingithe accompanying 'specifica- 5 ti'onand 'claims.

.2 I To obtain these=objectsof our invention, we. use in-the drillingmud asulfonatedcellulosederi-vative. "More specificallywe use those cellulose derivatives which may be regarded structurally 5 as being salts of 'cel-lulosealkane-, celluloseben- *z'ene- --or cellulosealkylbenzenesulfonic acids. "These may be prepared'ioy the reaction- 015 -cellulose with a halogenalkanesulfonic acidsuchas' 'betachloroethanesulfonic acid; a chlorobenzenel0 sulfonic acid," and-ranalpha-chloroalkylbenzenesulfonic acid such asalphachlorotoluenesulfonic acid. 'flie'saltsare the add-itionproducts of free acid 'andthe-Waten soluble sulfonatewcel-lulose derivative. These "compounds ar characterized by thetypical sulfonate linkage:

wherein Sis sulfurfo is'oxygen, ahd'C iscarbon. In celluloseeth'anesulfonic acid, the typical linkage appears as' follows:

a a Our cellulose is not precipitated or-regenerated 'bydilution with waterand/ or the usualsalt contained: in 'connate water. It is not precipitated 1 by heat -or cold'generallyobtainable in a-well nor is it regenerated during use as a drilling-fluid by -aging-or ripening. :It: is a substantially-stable I substance for rela-t-ivelyvlong periods 10f: time. Substanceswhich precipitate or: regenerateiunder the above conditionsare not-suitable for use: in drilling mud; although they may find some suse-as plugging agents-for plugging wells. Therefore, 40 they-are not relatedn to the present invention. Such plugging agents would soon .pr ecipitateand fillethe mud pit. and also c'hokethe drill 'stem' in the hole if used -as adril'ling fluid.

The :exact amount :ofwater soluble sulfonated cellulose-derivative employed is --notcritical "as =evenz small. amounts give a correspondinglysmall eiiect. These .sulfonated cellulose'derivativestmay beprepared- :byimany. methods known. .tothe: art. T he type. formula :forisulfonated:cellulosesderiva- .tives of the-above-acid is:

where: 3- 1 is fthe glucose' residue Gil-I102) ;-T "R" is an alkylene I? :iradical, such as a methylene 3 (-CHz-), ethylene (CH2CH2--), or 1,3- propylene (CH2CH2CH2--) radical, an alphaalkarylene radical, such as a benzylene alphamethylbenzylene among) or alphaethylbenzylene oniomcng) radical, or an arylene radical, such as a phenyl ene radical, and M is an alkali metal, an alkaline earth metal or ammonium group, and n is an integer. Other metal ions which form water soluble salts of the sulfonated cellulose may be used.

The degree of substitution is the average number of substituents per glucose residue. The average number of substituents in each unit of the cellulose derivatives should be sufficient to make the molecule water soluble. In general, the degree of substitution should be above 0.2 and may be as high as 3.0. However. complete substitution is not necessary. The additional expense of producing a completely substituted product is not warranted by the additional benefits gained over the water soluble, lower-substituted material.

The number of these indicated functional groups introduced into the cellulose is variable, depending on reaction conditions, and the variation will change the properties of the product to a certain degree. Only one functional group is indicated in the formula shown, but some X units may have all hydroxyl hydrogensreplaced while others may have none.

The sulfonated cellulose derivatives may be employed as free acids or in the form of the alkali metal. al aline earth metal and ammonium salts. On a free acid basis the ouantitv of these derivatives added to the mud may vary from about 0.1 to 2 or more pounds per barrel of conventional aqueous drilling mud com osition, but obviously more or less may be employed with some value.

Our sulfonated cellulose derivative combines the beneficial effect of other soluble cellulose derivatives on drilling muds with increased compatibilitv to conditions tending to accelerate the flocculation of the drilling mud colloids such as water of low pH. high salt content, or deleterious polyvalent cations such as barium, calcium, aluminum and others.

Anv use of the sulfonated cellulose derivatives described herein to be retained in the mud throughout the entire normal life of the drilling mud is not to be confused with the use of some cellulose which is to be precipitated as an insoluble plugging agent in the formation. Our cellulose derivatives are substantially stable to heat, cold. aging. ripening, dilution by water, and contamination by salts of connate water. Their use is not to be confused with plugging agents which are deliberately precipitated by such heat, cold, aging or dilution. We do not use our cellulose as a plugging agent. While minor reactions in the wellmay form a colloidal haze of supposedly insoluble cellulose and while this colloidal cellulose may contact the formation, such minor traces of insoluble colloidal material is not comparable to the immediate precipitation of relatively massive amounts of insoluble plugging material. Drilling muds containing our cellulose derivatives in the amount used (which may be about 4 pounds of cellulose per barrel of mud) are not subject to injury to any detrimental degree by the concentration of salt of the usual connate waters.

While we have found that the most satisfactory cellulose derivatives are those in which the alkylene portion of the functional group R contains 3 or less carbon atoms, the derivatives in which R contains more than 3 carbon atoms have varying degrees of usefulness.

Such drilling muds containing cellulose derivatives described herein often have low initial gel strengths, which allows gas bubbles to come out of the drilling mud so rapidly that the drilling mud will not become gas cut. Elimination of gas cutting reduces the chances of blowouts. Our drilling muds are often characterized by a relatively thin filter cake and by small water loss. This is very useful in avoiding loss of water to the formation, as well as the resultant swelling or caving of the formation which occurs with some formations. Our muds do not generally ferment or spoil.

The effectiveness of our sulfonated cellulose derivatives as mud-control agents will be more clearly understood from a consideration of the following examples. These are the results of tests which have been performed on the indicated derivatives under the particular conditions described in connection therewith.

EXAMPLE I Two samples of the potassium salt of celluloseethanesulfonic acid having degrees of substitution of 0.4 and 2.4, respectively, were prepared from a high grade chemical cotton and a third sample of the sodium salt of celluloseethanesulfonic acid having a degree of substitution of 1.51 was prepared from wood pulp. Since the material having a degree of substitution of 0.24 was found to give fairly high viscosities, a portion of it was treated with hydrogen peroxide to give a lower viscosity material. This sample of treated material will hereafter be referred to as modified 0.24. For the sake of simplicity, the material used in these tests will be designated by their respective degrees of substitution. The hydrogen peroxide merely degrades the material by breaking it into shorter cellulose chains. It is still the same material chemically.

EXAMPLE II The samples of potassium celluloseethanesulfonate were tested in a base mud and comprising 8.1 per cent Ezmix (native clay), 0.8 per cent bentonite, 26.3 per cent barium sulfate, 0.8 per cent barium carbonate, and 64 per cent water. The test procedure was to hydrate the amount of additive required for each test in 50 ml. of water for several hours, then add this volume to 250 ml. of base mud and stir for 30 minutes. The mud composition given above is for the diluted system. These sample muds were agitated for 30 minutes and allowed to stand overnight at room temperature. They were then stirred again and tested for viscosity, gel strengths, water loss, and pH according to procedures outlined in A. P. I. Code 91.01 The results were as shown in the following The sod um. cella qseetha esul onate hav ng a tat aa of; 1.5.1; alterar om i ahamu atleas'tBO. inutes. T e sam les e. hen ged; overnight atroom temperature and then tested according o the n ard p c r he sul were as shown in the following tablet,

Table 2 Viscosity, cps; 1s 24. s as 100 100 nitia l streng h, ms- 0 0 0 r 0 25 10 min. 'gel strength, gms 5 0 80 160 Water loss, ml. in min. at 100 p. s. L. 17 13. 5. 10. 6 6.0 4. 4 7- 9 8-.0.

A. s m e. at odium. cel ul seniethrl en nel onat f' h v ng a de ee fsubs u 0.5 as rep red. y he reac ion, a chemical n. with sod um. alpha h or t luenesulfonate- This mate ial was tested in hree different m sys emsthe composit ons o.f ,whieh. re.shown in the fo lowin tab e:

Tab as q etiti e ia ea ate t desigliilgg Keelia- $3528 .33 5 BaSQe 11.2

n 5.0. o.- 575 .6 15 has 1am 59,18

The mud" designation KB refers to Kaolinbentonite, EB refers to E-Zmix-bentonite, and EBSrefers to EzmiX-bentonite-salt.

I each test the required dosaeeof add tiyewas weighed on he r has andacldecl to he m which was. then stirred for 3.0 minutes. The sam leswere allowed. to stand ov rn ght at r om mp r tu fter whi h hey were tested for s y. gel stren th. water oss. and pH accord ng athe .stan ardproc dures The. r su ts ofthese tests were. as shown. in the iOllQWiIlg table;

Sodium cellulosemethylr Mir! bsnaen ul onate des gnation Pounds per barrel 0 1 Z, 4 6,

sqo tmcn -w 1,8 26 4 3. In tial gel strength, g ns... 0 I 0 0 0 5 .10:min...ge :str n he s, 5. t 2, 1' 7 .0 v a) .Water10ss,,n; h.3 mi at S 1' 17- 14.5 11.5 7:7 -5.5 DH--.--- ;-9 1-0 8-, 8: 8:2 Viscos 12 ll 10 10 10 Initial gel strength, gms 19 1'2 12- 5 0 EB 10 min. gel strength, gins. 20 12 12 8 7 Water loss, ml, in 30 min. i

at 100 p. i 56.5 58 50 37 25 8.2- 7.9 7.8 7.9 7.9 V1scosity,cps 18 l0 l0 10 12 Initial gelalstrtgengtilfig lg l2 17 1g tmi itsw ren ,s 3., .5 0 Wa e 1038, m1- 1 0' l 2.11.100: an. 57 5 58- 5s 48; 4,3- I. 7 6 Z4, 7 2 -2;

His understood 'that while a theory ofopera: tion has been advanced, it is-not' the only; or-necessary one, but has been advanced only to facilitate the disclosure. It isunderstood, however, that this invention is not limited to any theory oi operation oraction. It is further obvious that various changes may be made in the details without departin from the spirit of this invention, or'from the scope of the invention as defined in the following claims. Obviously, use in aqueous mud laden fluids includes use in the aqueous phase ofan emulsion or mixture with nonaqueousmaterial. It'is understood that the invention is not to be limited to the specific details described. For example, tests with treating and control agents indicate that thes celluloses are somewhat inert chemically and that all the normal and usual treating and; control agents of the well drilling fluid and well controlling fluid arts may, after a simple test forlack of obvious adverse reactions, be employed without invention in our cellulose drilling and controlling fluids, and that with few, if any, exceptions they will be so employable. Our invention is, therefore, to be defined by the following claims:

We claim:

1;. A process-for forminga filter cake, having a low rate of filtration of fluid therethrough, on the wall of a well by the deposition of colloidal clayey solids from a water-base drilling mud circulated along said wall which comprises admixing with said drilling mud and interacting therewith a water. soluble sulfonated cellulose derivative having the general formula:

wherein X is the glucose residue (*C'sHzOa) R is a radical selected from the group consisting of alkylene radicals wherein the alkylene group contains from 1 to 3 carbon atoms, alkylenephenylene radicals where the alkylene portion of thegroup contains from 1 to 3 carbon atoms and is linked to the glucose residue through the alpha carbon atom, and the phenylene radical; S03 is a sulfonate group; M is-of the group consisting of an alkali metal, an alkaline earth metal and an ammonium radical; n is an integer; a sufficient number of the hydroxyl hydrogens being replaced to render the moleculewater soluble; vSaid water soluble sulfonated cellulose derivative being incorporated in said drilling mud in an amount. .sufiicient to decrease the rate of ultra,

7 tion oi. fluid through said filter cake but insufficient to increase the viscosity of said drilling mud to such an extent as to render it uncirculatable and contacting said wall of said well with the: resulting drilling mud to form said filter cake thereon.

2. A water base well drilling mud comprising in combination sufiicient water to maintain the mud as a fluid, sufiicient clayey material to form a filter cake on the wall of the well, and a water soluble sulfonated cellulose derivative having the general formula:

wherein X is the glucose residue (CeHqOz); R is a radical selected from the group consisting of alkylene radicals wherein the alkylene group contains from 1 to 3 carbon atoms, alkylenephenylene radicals wherein the alkylene portion of the group contains from 1 to 3 carbon atoms and is linked to the glucose residue through the alpha carbon atom, and the phenylene radical; S03 is a sulfonate group; M is of a group consisting of an alkali metal, an alkaline earth metal or an amonium radical; n is an integer; a sufiicient number of the hydroxyl hydrogens being replaced to render the molecule water soluble; said water soluble sulfonated cellulose derivative being incorporated in said drilling mud in an amount suificient to reduce the water loss due to filtration through said filter cake but insuflicient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

3. A water base well drilling mud comprising an aqueous fluid mixture containing suspended inorganic solids which form a filter cake on the wall of the well, and a water soluble sulfonated 4 derivative having the general formula:

wherein X is the glucose residue (Cal-I702) R is a radical selected from the group consisting of alkylene radicals wherein the alkylene group contains from 1 to 3 carbon atoms, alkylenephenylene radicals where the alkylene portion of the group contains from 1 to 3 carbon atoms and is linked to the glucose residue through the alpha carbon atom, and the phenylene radical; S03 is a sulfonate group; M is of a group consisting of an alkali metal, an alkaline earthmetal or an ammonium radical; n is an integer; a sufiicient number of the hydroxyl hydrogens being replaced to render the molecule water soluble; said water soluble sufonated cellulose derivative being incorporated in said drilling mud in an amount sufiicient to reduce the water loss due to filtration through said filter cake but insuificient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

4. A process for forming a filter cake, having a low rate of filtration of fluid therethrough, on the wall of a well by the deposition of colloidal clayey solids from a water base drilling mud circulated along said wall which comprises admixing with said driling mud and interacting therewith a water soluble inorganic salt of cellulosemethane sulfonic acid in an amount suflicient to decrease the rate of filtration of fluid through said filter cake but insuificient to increase the viscosity of said drilling mud to such an extent as to render 8. it uncirculatable and contacting said wall of said well with the resulting drilling mud to form said filter cake thereon.

5. A water base well drilling mud comprising,

in combination, sufficient water to maintain the mud as a fluid, sufiicient clayey material to form a filter cake on the wall of the well, and a water soluble salt of cellulosemethanesulfonic acid in an amount sufficient to reduce the water loss due to filtration through said filter cake but insu'ificient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

6. A water base well drilling mud comprising an aqueous fluid mixture containing suspended inorganic solids which form a filter cake on the wall of the well, and a water soluble salt of cellulosemethanesulfonic acid in an amount sufiicient to reduce the waterless due to filtration through said filter cake but insufiicient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

7. A process for forming a filter cake, havin a low rate of filtration of fluidtherethrough, on the wall or a well by the deposition of colloidal clayey solids from a water base drilling mud circulated along said wall which comprises admixing with said drilling mud and interacting therewith a water soluble salt of celluloseethanesulionic acid in an amount suificient to decrease the rate of filtration of fluid through said filter cake but insufficient to increase the viscosity of said drilling mud to such an extent as to render it uncirculatable and contacting said wall of said well with the resulting drilling mud to form said filter cake thereon.

8. A water base well drilling mud comprising, in combination, sufficient water to maintain the mud as a fluid, sufficient clayey material to form a filter cake on the wall of the well, and a water soluble salt of celluloseethanesulfonic acid in an amount sufficient to reduce the water loss due to filtration through said filter cake but insufiicient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

9. A water base well drilling mud comprising an aqueous fiuid mixture containing suspended inorganic solids which form a filter cake on the Wall of the well, and a water soluble salt of celluloseethanesulfonic acid in an amount suflicient to reduce the water loss due to filtration through said filter cake but insufficient to increase the viscosity of said drilling mud to such an extent that it cannot be circulated.

10. A process'for forming a filter cake, having a low rate of filtration of fluid therethrough, on the wall of a well by the deposition of colloidal clayey solids from a water base drilling mud cirljculated along said wall which comprises admixing with said drilling mud and interacting there- .with a water soluble salt of cellulosemethylbenzenesulfonic acid in an amount sufficient to decrease the rate of filtration of fluid through said filter cake but insufficient to increase the viscosity of said drilling mud to such an extent as to render it uncirculatable and contacting said wall of said well with the resulting drilling mud to form said filter cake thereon.

11. A water base well drilling mud comprising, in combination, sufficient water to maintain the mud as a fluid, sufficient clayey material to form a filter cake on the wall of the well, and a water soluble salt of cellulosemethylbenzenesulfonic acid in an amount sufiicient to reduce the water loss due to filtration through said filter cake but insufficient to increase the viscosity of said drill- 9 10 ing mud to such an extent that it cannot be cir- REFERENCES CITED culated' The following references are of record in the 12. A waterbase well drilling mud comprisin fil of this an aqueous fluid mixture containing suspended p inorganic solids which form a filter cake on the 5 UNITED STATES PATENTS wall of the well, and a water soluble salt of cellulosemethylben'zenesulfornc acid in an amount fig g 333 et a1 g sufiicient to reduce the water loss due to filtra- 2425'768 Wagner 1947 tion through said filter cake but insufllclent to 2489'521 Carlson 1949 increase the viscosity of said drilling mud to such 10 an extent that it cannot be circulated.

CARY R. WAGNER. WILLIAM N. AXE. CHESTER M. HIMEL. 

1. A PROCESS FOR FORMING A FILTER CAKE, HAVING A LOW RATE OF FILTRATION OF FLUID THERETHROUGH, ON THE WALL OF WELL BY THE DEPOSITION OF COLLOIDAL CLAYEY SOLIDS FROM A WATER BASE DRILLING MUD CIRCULATED ALONG SAID WALL WHICH COMPRISES ADMIXING WITH SAID DRILLING MUD AND INTERACTING THEREWITH A WATER SOLUBLE SULFONATED CELLULOSE DERIVATIVE HAVING THE GENERAL FORMULA: 